Loughborough University Institutional Repository: The citation advantage of open access articles (2008)
peter.suber's bookmarks 2013-11-16
Summary:
Abstract: Four subjects, ecology, applied mathematics, sociology and economics, were selected to
assess whether there is a citation advantage between journal articles that have an open
access (OA) version on the Internet compared to those articles that are exclusively toll
access (TA). In two rounds of data collection, citations were counted using the Web of
Science and the OA status of articles was determined by using the search tools OAIster,
OpenDOAR, Google and Google Scholar. In the first round a purposive sample of 4633
articles for the four subjects from high impact journals were examined, 2280 (49%) were
OA and had a mean citation count of 9.04, whereas the mean for TA articles was 5.76.
There was a clear citation advantage for those articles that were OA as opposed to those
that were TA. This advantage, however, varied between disciplines, with sociology
having the highest citation advantage but the lowest number of OA articles from the
sample taken and ecology having the highest individual citation count for OA articles but
the smallest citation advantage. Tests of correlation between OA status and a number of
variables were generally found to be weak or inconsistent but some associations were
significant. Google and Google Scholar were more successful at finding OA articles on
the Internet than were OAIster or OpenDOAR. The country of origin of the citing authors
for applied maths was found in order to assess whether those authors from poorer
countries cited OA articles more frequently than TA articles. While cited to citing article
ratios from lower income countries favoured OA articles, overall percentages gave mixed
results. The data from the second round confirmed the result for sociology. The second sample
for ecology was randomly taken from 82 journals and exhibited a greater OA advantage.
For economics, a second purposive sample of articles from 21 mid-range impact journals
was taken and also exhibited a greater OA advantage. In an attempt to establish the cause
of any citation advantage, logistic regression was used to try to determine whether the
bibliographic characteristics of the articles from both rounds could be used to predict OA
status. Results from this were generally inconclusive..